Method of cracking hydrocarbon oils



May 24, 1932,. R. c. osTERSTRoM METHOD OF CRGKING HYDROCARBON OILS Filed April so', 1929 Y QSS Qmulmw MSSS:

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\ Raad ersrom Patented May 2 4, 1,932

UNITED STATES PATENT .OFFICE RUDOLPH c. Osriansmnou, OF OHIOAG'OJLLINOIS,AssIGNOR 'ro THE PURE OIL com- PANY, or CHICAGO, ILLINOIS, A CORPORATION OF OHIO Application led April 30,

5 ing points from compounds having higher boiling points. In accordance with the invention, there is provided a method for accomplishing this purpose wherein theoil unvmolecular rearrangements.

dergoing decomposition is passed in a continuously moving stream through a heated cracking zone and subjected to conditions of temperature and pressure for maintaining the oil during the cracking step in the vapor phase, although in certain other aspects of my invention the cracking temperatures and pressures may be so regulated that the oil is maintained substantially in the liquid phase during conversion.

It is a primary object of the invention to introduce into the oil undergoing conversion continuously added quantities of a contact or catalytic material, such as fullers earth, which flows or passes in unison with the oil through the cracking zone in a finely divided and uniformly distributed state through the entire body of the oil subjected to cracking conditions, the presence of said material in the oil serving first, to facilitate cracking reactions, second,'to minimize the formation of fixed gas and, third, to virtually eliminate coke or carbon liberation.' In vapor phase systems particularly of oil conversion it is a very difficult matter to minimize fixed gas and coke production. This is due primarily to the fact that the oils undergoing conversion are heated to relatively high temperatures usually in excess of 1000o F., and under the infiuences of these temperatures the oils are highly reactive and Subj ect to violent l This unstable condition results not only in the breaking down of the hydrocarbons into molecular groups falling within the boiling range of motor fuels, but also inthe formation of a veryconsiderablequantity of lighter hydrocarbons ordinarily known as fixed gas. Due to the character of the reactions, free or uncombined carbon, known as coke, is likewise released un^der high cracking temperatures, and if uncontrolled this carbon tends nllIE'lHOD 0F 'CRACXING HYDROCARBON OILS 1929. Serial No. 359,248. v

to obstruct the oil circulating passages or tubes of the cracking zone and adjacent apparatus, thereby interfering seriously with the proper function of the system.

I have discovered that the addition of fullers earth to the charging stock passing continuously through the cracking zone serves in the manner of a catalyst not only in the matter of facilitating the breaking down of the high boiling compounds into those of lower boiling point, but also in the matter of minimizing coke and gas formation. Cracking reactions are usually reversible. That is to say not only are lighter compounds produced but at the same time heavier cornpounds are built up. It is my present theoryr that due to the presence of the fullers earth in a finely divided, constantly changing and uniformly distributed mass throughout the moving oil body undergoing decomposition, that the gas liberated as a result of the cracking reactions is also polymerized bythe cracking temperatures and the presence of the catalytic materials. The gas in polymerizing' combines with the free carbon available and produces the heavier compounds which can be subsequently collected and possess boiling ranges equivalent tomotor fuel distillates.

I am aware of the fact that it has `been proposed heretofore toplace a stationary bed of fullers earth in an oil cracking still or zone. The present invention, is, however, distinguished from such earlier methods by the fact that ,the fullers earth, or other equivalent -contact or catalytic materials,l

essary in attaining the objects and advantages hertofore pointed out.

Again, the invention further serves in effectively treating the oil while it is being cracked for the purpose of removing certain undesirable compounds therein. Charging stbcks for oil cracking systems contain certain impurities suchv as gums, color imparting bodies and in many instances sulphur. I have found that by cracking the charging stock, as above stated, these'undesirable compounds may be readily removed and sepa-v rated from the desirable fractions, with the result that treatment of the latter, in the removal of such undesirable bodies, is greatly lightenedfollowing the cracking step, and the process of producing motor fuels is generally expedited and economic benefits secured.

It is a further object of the invention to fractionate the products discharged from the cracking zone in order to remove from the system the liquid clay-bearing fraction, which contains the heavier compounds, from the desired lighter and vaporous fractions. The clay-bearing liquid is then preferably passed through a filter press to separate the clays from the liquid oil.

For a further understanding of the details of the process, reference is to be had to the following description and the accompanying drawing, wherein the figure illustrates diagrammatically apparatus which may be used in carrying my invention into practical operation.

Referring more particularly to the drawing, the numeral 1 designates a supply tank adapted to contain the charging stock. The

oil is drawn from the supply tank by wayv of a pipe line 2 and pump 3 and is forced through a pipe still 4 comprising a primary heater. In this form of my invention, the oil while circulating through the tube bank 5 within said still is subjected to temperatures sufficiently high to effect vaporization of a larger proportion of the total quantity of oil passing through the still. Theinternal temperature of the still is, however, regulated to prevent any substantial cracking of the oil passed therethrough. These temperatures may be of the order of approximately 700 to 7 50 F. From thev still 4 the oil products are passed by way of a pipe line 6 into an evaporator 7 wherein there takes place a separation of the` desired vaporous fractions of the oil from the heavy, undesirable liquid fractions. These liquid fractions are withdrawn from the bottom of the evaporator by way of a pipe line 8 and may be promptly removed from the system. The desired vaporous fractions pass overhead from the evaporator 7 through a pipe line 9 and within this pipe line the vaporized oil is intimately mixed with -continuously supplied quantities of the contact or catalytic materials, preferably fullers earth, although, yof course, other equivalent materials may be utilized.

One method of adding the fullers earth to the vaporized oil consists in'A providing a hopper or magazine 10 in 'which the fullers earth is contained. The bottom of this magazine opens to a'. conduit 11 in which is arranged a spiral type of conveyor 12 actuated by a variable speed motor-13. By controlling the operation of the motor 13 the rate of input of the fullers earth into the line 9 may be regulated. It will be understood that certain oils require a greater quantity of fullers earth to secure desired results than other oils. For this reason, it is desirable to provide adjustment in the matter of introducing the fullers earth into the system.

After the fullers earth has been added to the oil in the line .9 it moves in unison in a uniformly distributed manner with said oil vapor 'and passes with the latter into a cracking still 14.- Howing through the tubularv elements 15 of said still under conditions of tures are, of course, subject to variation. Y

From the still 14 the oil vapor is passed through a line 17 containing a valve 18, if desired. and thenceinto an evaporator 19 and a fractionating tower 19. Within the evaporator 19 the lighter or vaporous fractions pass upwardly while the heavier compounds move to the bottom and are collected in the latter as a liquid. This liquid fraction also contains the clay or fullers earth forced into the system at the line 9, thus permitting of separation of the clay from the desired lighter, cracked distillates produced by the system.

The lighter distillates pass from the top of the fractionating tower by way of a line 20, thence through a condenser 21 and a. gas separator 22. and are finally received as a finished or substantially finished end product in the storage tank 23. With certain charging stocks, the end product received within the tank 23 constitutes a finished motor fuel and is -ready for commercial distribution, although in the matter ofvother charging stocks some additional treatment for purification purposes may be given, if deemed necessary.

The clay-liquid fraction which collects in the bottom of the evaporator-'19, is removed by way of a pipe line 24 and is forced b-y a pump 25 through a filter press 26, which serves to separate the clay from the liquid oil by a pressure-filtering operation. The

clay-freed oil may then be passed through a cooler or heat exchanger 27 and delivered to a storage tank 28. or maybe returned to the tank 1 for re-circulation, if desired.

The invention thus provides for the introduction of fullers earth or other equivalent materials in a finely `divided form into 1,sco, 199 l 4 the charging stock of a cracking still, wherereduces the quantity of fixed gas or the inconin the clay moves in unison with the continuously moving bodies of oil passin through the cracking still. As above state ,the clayl serves in the capacity of a catalyst, using that term in its accepted sense,'promoting, first,

-the molecular decomposition of the charging stock passing through te still or converter by the breaking down of the higher boiling compounds, such as a gas-.oil or kerosene fraction, 4into compounds lhaving the boilin range of gasoline. Second. the ullers eart densables developed by the operation of the converter' and the formation of free carbon, by promoting reactions of a polymerizing character by Awhich the ixed gas and free carbon are combined into compounds liquefiable at"l ordinary temperatures and, third, the presence of the ullers earth in the cracking still serves to remove from the oil bodies which tend to -produce gums or undesirable color in the finished endproduct. These advantages are largely attributed to the presence of the finely divided contact or catalytic material in the oil stock undergoing conversion and to the form and distribution of the contact or catalytic materials in said stock. The invention is particularly applicable and its benefits are quite marked when the oil nndergoing conversion ismaintained in the o vapor phase and subject to high temperatures ofY the order of 1000F. Under such4 conditions carbon and gas are formed rapidly and therefore the present invention is admirably suited incontrolling or regulating the same'. In -liquid phase operations carbon liberation and gas formation are not quite so pronounced', but the invention also finds a'wide field of use therein. If desired, the fixed gas released from the separator 22 may be recirculated through the converterA for additional treatment or the gas may be passed to a suitable point of storage.

What is claimed is:

1. The process of converting high boiling petroleum hydrocarbons into low boiling pe.- trolenm hydrocarbons, which comprises pass ing the vapors of high -boiling petroleum hydrocarbon oils commingled with fullers earth through a heated zone maintained at a temperature in excess of 1000 F., and fractionv ating the vapors discharged from said heated zone to separate fractions.

2. In the process of makingglow boiling petroleum hydrocarbons from high boiling-l petrolenm hydrocarbons, the process which the light from'the Aheavy o rately condensing and collectin said low boiling oils, and subjecting the hlgh boiling oils to a filtering operation to remove therefrom its fullers earth content.

3. The method of 'convertinghigh boiling hydrocarbon oils into low boiling hydrocarbon oils, which consists in passing a steam of such high boilin oils in a vaporlzed condition and intimatly commingled with fullers earth through an elongated exteriorly heated conversion zone of restricted crosssectional area, in regulating the rate' of travel of said mixture of fullers earth and vaporized oil through the conversion zone and the application of heat to said zone to raise the tem erature of said mixture for a desired perio of time to converting temperatures in excess of 1000 F., passing the'inixture from the conversion zone to an enlarged separating zone, therein reducing the pressure on said mixture and lowering the temperature thereof sufiiciently to effect the separation of the undersired high boiling oils as liquids together with the ullers earth from the desired converted oils of low boiling range re' comprises passing the vapors of'such high l boiling oils through a. heated zone at a tem peratnre of about 1000 F. admixed with a catalyst having the properties of fullers earth, fractionating the vapors removed from said heated zone to separate-'the desiredlow boiling oils from the high boiling oils, sepaaoy 

